Electric motors (e.g., AC or DC electric motors) are used in a wide variety applications, such as in fans to rotate a propeller blade, and in disk drives to rotate magnetic disks. To these and other ends, electric motors have two primary portions; namely, a stationary portion (“stator”) that produces a varying magnetic field, and a rotational portion (“rotor”) that rotates in response to the magnetic field produced by the stator. The rotor typically is fixedly secured to one end of a shaft, while the stator is rotatably secured to the other end of the shaft. The rotor and shaft thus rotate as a single unit (effectively acting as a single rotor) at a speed controlled by the magnetic field produced by the stator.
During operation, torsional and rotational stresses can be applied to the point where the shaft couples with the rotor. To ensure proper operation of the motor, it therefore is important to ensure that this coupling point can withstand anticipated operating stresses. Many currently available motors nevertheless secure the shaft to the rotor with a moldable material (e.g., zinc) that is less rigid than the materials making up the rotor and the shaft. Because of this relative softness, the moldable material often does not provide a sufficient coupling. Consequently, the shaft may uncouple from the rotor, causing the motor to fail. When the motor is a part of a cooling fan, for example, this failure can cause catastrophic failure of an underlying device it is cooling (e.g., a server or other computer device).